车桑子小孢子发生与雄配子体发育

Microsporogenesis and Male Gametophyte Development of Dodonaea viscosa

摘要:

为了解干热河谷区车桑子（Dodonaea viscosa）胚胎学特征及其结籽率低的原因，采用常规石蜡切片法和电镜扫描技术对车桑子小孢子发生、雄配子体发育和花粉的形态特征进行了观察。结果表明，车桑子花药具有4个花粉囊。完整的花药壁从外到内依次为表皮、药室内壁、2~3层中层细胞和绒毡层；绒毡层类型是腺质绒毡层。花药成熟期，中层、绒毡层均退化消失。小孢子母细胞进行同时型胞质分裂；四分体为四面体型结构。成熟的花粉为二细胞型。花粉近球形，外壁密布颗粒状纹饰，具有3条不构成合沟的萌发沟。雄性生殖发育过程出现的异常现象可能是干热河谷地区车桑子结籽率低的原因之一。

Abstract:

To understand the embryological characteristics of Dodonaea viscosa in the dry and hot valley and the reasons for its low seed setting rate, microsporogenesis, male gametophyte development and pollen morphological characteristics of D. viscosa were studied with traditional paraffin sections and scanning electron microscopy. The results showed that the anther of D. viscosa had four pollen sac. The anther wall was composed of the epidermis, the endothecium, 2-3 middle layers, and tapetum (glandular tapetum) from the outside to the inside; at anther mature stage, the middle layer and tapetum denegerated and disappeared. The cytokinesis occurred simultaneously in a microspore mother cell; the tetrad was tetrahedral. The mature pollen was two-celled type. The mature pollen grain was nearly spherical with granular ornamentation on exine and 3 germ furrows which did not form syncolpate. Our researches showed that some abnormal phenomenon in male reproductive development might be one of the reasons of low seed setting rate.